A solvent‐assisted grinding method has been used to prepare co‐crystals in substituted dihydropyrimidines (DHPM) that constitutes pharmacologically active compounds. These were characterized using FT‐IR, PXRD, and single‐crystal X‐ray diffraction. In order to explore the possibility of formation of halogen (XB) and hydrogen bonding (HB) synthons in the solid state, co‐crystallization attempts of differently substituted DHPM molecules, containing nitro, hydoxy, and chloro substituents, with different co‐formers, such as 1,4‐diiodo tetrafluorobenzene (1,4 DITFB) and 3‐nitrobenzoic acid (3 NBA) were performed. The XB co‐crystals (C2aXB, C2bXB, and C2cXB) prefer the formation of C−I⋅⋅⋅O/C−I⋅⋅⋅S XB synthon, whereas the HB co‐crystal (C2dHB) is stabilized by N−H⋅⋅⋅O H‐bond formation. Hirshfeld surface analysis revealed that the percentage contribution of intermolecular interactions for XB co‐crystals prefer equal contribution of XB synthon along with HB synthon. Furthermore, the interaction energy was analyzed using energy frameworks, which suggests that their stability, a combination of electrostatics and dispersion, is enhanced through XB/HB in comparison to the parent DHPMs.
A series of 4-cyano-4′-alkoxybiphenyl compounds were synthesized by varying the spacer chain lengths (−CH 2 −) n , where n = 3−10, for the systematic study of a halogen-bonded (XB) complex with 1,4-diiodotetrafluoro benzene. The XB liquid crystalline complexes obtained from the liquid-assisted grinding method were characterized by FTIR, Raman, DSC, and PXRD studies. Further, C�N•••I XB interaction was established by singlecrystal X-ray diffraction analysis. The odd-even analysis has suggested that the even carbon chain length containing XB liquid crystalline complexes shows slightly higher alteration in their isotropic temperature compared to the odd carbon chain lengths of such complexes. Furthermore, it is interesting to note that the higher alkyl chain complexes (n = 6−10) showed liquid crystalline temperature at lower values with respect to their ligands. The Hirshfeld and energy framework analyses have also been carried out to assess the stability and percentage contribution of XB noncovalent interaction. The frontier molecular orbital, noncovalent interaction, molecular electrostatic potential, and QTAIM analysis were performed using DFT to evaluate the nature of XB in these halogen-bonded liquid crystalline systems.
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